Screwed myself...AGAIN!!

I had a buddy order everything to build a detachable mag .338 Lapua. The builder mistakenly chambered it for .338 Edge. He used it on our elk hunt and the mag wouldn't hold but a single round without popping them out. The .338 Lupua brass has more girth and the lips can't keep the rounds secured under pressure. His needs altered.
I don't know which bottom metal/mags he has so I can't say if you'll have that problem.

WOW. How about the bolt face? Did the donar action have a .532 boltface or the bigger Lapua bolt face? I am thinking that it had to be the correct one, because I wouldn't be in the same county when he pulled the trigger if it were wrong!!!!

Well, it looks like I resolved the issue. Took the mag up to my local, brother-in-law owned machine shop and had him mill out, little by little, the BACK side of the front groove.....worked his way forward just enough to let the sholders pass. We left the front part of the grove in place, keeping contact with the sholder, which in turn keeps the case from slamming forward into the front of the mag during recoil. Thus, the bullet points are still protected and my OAL won't change with each shot.